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A163793
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a(n) is the n-th J_13-prime (Josephus_13 prime).
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2
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5, 57, 117, 187, 251, 273, 275, 665, 2511, 40393, 48615, 755921, 970037
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OFFSET
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1,1
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COMMENTS
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Place the numbers 1..N (N>=2) on a circle and cyclicly mark the 13th unmarked number until all N numbers are marked. The order in which the N numbers are marked defines a permutation; N is a J_13-prime if this permutation consists of a single cycle of length N.
There are 13 J_13-primes in the interval 2..1000000 only. No formula is known; the J_13-primes have been found by exhaustive search.
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REFERENCES
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R. L. Graham, D. E. Knuth & O. Patashnik, Concrete Mathematics (1989), Addison-Wesley, Reading, MA. Sections 1.3 & 3.3.
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LINKS
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EXAMPLE
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All J_13-primes are odd.
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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